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author | Raymond Hettinger <rhettinger@users.noreply.github.com> | 2018-01-16 09:30:26 (GMT) |
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committer | GitHub <noreply@github.com> | 2018-01-16 09:30:26 (GMT) |
commit | b44c5169f64178d2ff2914187b315549e7ab0cb6 (patch) | |
tree | a6123ca1509df2bc83fd36a275f95f58e735e869 | |
parent | 94e1696d04c65e19ea52e5c8664079c9d9aa0e54 (diff) | |
download | cpython-b44c5169f64178d2ff2914187b315549e7ab0cb6.zip cpython-b44c5169f64178d2ff2914187b315549e7ab0cb6.tar.gz cpython-b44c5169f64178d2ff2914187b315549e7ab0cb6.tar.bz2 |
bpo-26163: Frozenset hash improvement (#5194)
-rw-r--r-- | Misc/NEWS.d/next/Core and Builtins/2018-01-14-20-32-47.bpo-26163.xv9Iuv.rst | 2 | ||||
-rw-r--r-- | Objects/setobject.c | 1 |
2 files changed, 3 insertions, 0 deletions
diff --git a/Misc/NEWS.d/next/Core and Builtins/2018-01-14-20-32-47.bpo-26163.xv9Iuv.rst b/Misc/NEWS.d/next/Core and Builtins/2018-01-14-20-32-47.bpo-26163.xv9Iuv.rst new file mode 100644 index 0000000..163b9e0 --- /dev/null +++ b/Misc/NEWS.d/next/Core and Builtins/2018-01-14-20-32-47.bpo-26163.xv9Iuv.rst @@ -0,0 +1,2 @@ +Improved frozenset() hash to create more distinct hash values when faced +with datasets containing many similar values. diff --git a/Objects/setobject.c b/Objects/setobject.c index c920fb9..4bc1020 100644 --- a/Objects/setobject.c +++ b/Objects/setobject.c @@ -795,6 +795,7 @@ frozenset_hash(PyObject *self) hash ^= ((Py_uhash_t)PySet_GET_SIZE(self) + 1) * 1927868237UL; /* Disperse patterns arising in nested frozensets */ + hash ^= (hash >> 11) ^ (~hash >> 25); hash = hash * 69069U + 907133923UL; /* -1 is reserved as an error code */ |